target-arm: Correct conversion of Thumb Neon dp encodings into ARM

Submitted by Peter Maydell on Feb. 11, 2011, 1:35 p.m.

Details

Message ID 1297431325-17371-1-git-send-email-peter.maydell@linaro.org
State New
Headers show

Commit Message

Peter Maydell Feb. 11, 2011, 1:35 p.m.
From: Juha Riihimäki <juha.riihimaki@nokia.com>

We handle Thumb Neon data processing instructions by converting them
into the equivalent ARM encoding, as the two are very close. However
the ARM encoding should have bit 28 set, not clear. This wasn't causing
any problems because we don't actually look at that bit during decode;
however it is better to do the conversion correctly to avoid problems
later if we add checks to UNDEF on SBZ/SBO bits.

Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/translate.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

Comments

Aurelien Jarno Feb. 20, 2011, 4:31 p.m.
On Fri, Feb 11, 2011 at 01:35:25PM +0000, Peter Maydell wrote:
> From: Juha Riihimäki <juha.riihimaki@nokia.com>
> 
> We handle Thumb Neon data processing instructions by converting them
> into the equivalent ARM encoding, as the two are very close. However
> the ARM encoding should have bit 28 set, not clear. This wasn't causing
> any problems because we don't actually look at that bit during decode;
> however it is better to do the conversion correctly to avoid problems
> later if we add checks to UNDEF on SBZ/SBO bits.
> 
> Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  target-arm/translate.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)

Thanks, applied.

> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 3087a5d..793fd59 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -8011,7 +8011,7 @@ static int disas_thumb2_insn(CPUState *env, DisasContext *s, uint16_t insn_hw1)
>          /* Coprocessor.  */
>          if (((insn >> 24) & 3) == 3) {
>              /* Translate into the equivalent ARM encoding.  */
> -            insn = (insn & 0xe2ffffff) | ((insn & (1 << 28)) >> 4);
> +            insn = (insn & 0xe2ffffff) | ((insn & (1 << 28)) >> 4) | (1 << 28);
>              if (disas_neon_data_insn(env, s, insn))
>                  goto illegal_op;
>          } else {
> -- 
> 1.7.1
> 
> 
>

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diff --git a/target-arm/translate.c b/target-arm/translate.c
index 3087a5d..793fd59 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -8011,7 +8011,7 @@  static int disas_thumb2_insn(CPUState *env, DisasContext *s, uint16_t insn_hw1)
         /* Coprocessor.  */
         if (((insn >> 24) & 3) == 3) {
             /* Translate into the equivalent ARM encoding.  */
-            insn = (insn & 0xe2ffffff) | ((insn & (1 << 28)) >> 4);
+            insn = (insn & 0xe2ffffff) | ((insn & (1 << 28)) >> 4) | (1 << 28);
             if (disas_neon_data_insn(env, s, insn))
                 goto illegal_op;
         } else {